As far as the first, yellow jackets are dicks a lot of times. Don't slam down slow runs. I usually look to see if there are yellow jackets as I'm coming down, and try and check even more speed if I see them. IF you do get hassled, usually best to dip and leave for the day. Not tell them your name, and just walk away. Don't yell at them or talk shit, but just calmly exit stage left.
As fare as closed terrain, don't do it. Even non yellow jacket mtns will pull tickets and sometimes passes for the season for that. Ski patrol will be on you as hard. Almost always, trails are closed for a reason. There's a huge responsibility on the mountain and patrol to provide a safe skiing experience. Sometimes it's avy danger, sometimes the coverage is super thin, sometimes there are cats working.
I've seen people duck ropes for a pow run early season that went from like 1.5' deep at the top, to like 2" at the bottom of wet shit snow with no base. Was thinking how dumb it would be to get your pass pulled for 2 decent turns, and then a stone grind fest that ended with a sad hike out.
Have seen many times people ducking ropes and going past cat working signs. People are just trying to do their job, nobody is trying to have some guy ski into their cat and get killed.
Also people ducking runs where snowmaking was going on. Either heinous half ice, half glue whales, or half pushed out runs with huge ledges, chunder fields, or froze track marks. Again super sick to ski frozen track pack, def worth getting your pass pulled.
When you think about it there are constant dangers out there that patrol and other departments are trying to mitigate. The few times that maybe a trail doesn't need to be closed, or you don't think it does, are not worth fucking with. If it's closed it's generally for a good reason whether or not you agree.